1. Field of the Invention
The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same, and particularly to a solid electrolytic capacitor including an anode body formed of a sintered compact, and a method for manufacturing such solid electrolytic capacitor.
2. Description of the Related Art
A solid electrolytic capacitor has been conventionally known as a capacitor suitable for size reduction. This solid electrolytic capacitor is manufactured as follows. First, valve metal powder such as, for example, tantalum (Ta) is molded into a molded body having a predetermined shape and the molded body is sintered, thereby forming an anode body. Next, a surface of the anode body is subjected to electrolytic oxidation treatment, thereby forming a dielectric coating. Next, using chemical polymerization or electrolytic polymerization, a conductive polymer layer is formed to cover the dielectric coating. This conductive polymer layer is referred to as a solid electrolyte layer, and is formed to reduce the equivalent series resistance.
Next, a carbon layer is applied to cover the solid electrolyte layer and a silver paste layer is further applied to cover the carbon layer, thereby forming a cathode layer. A capacitor element including the anode body, the dielectric coating, the solid electrolyte, and the cathode layer is thus formed. Next, the capacitor element is put on a predetermined lead frame and sealed with an exterior resin. As a result, a solid electrolytic capacitor is completed. It is to be noted that Japanese Patent Publication No. 04-74853 is one example of the literatures disclosing the solid electrolytic capacitor.
As described above, in the solid electrolytic capacitor, the solid electrolyte layer covering the dielectric coating is formed using chemical polymerization or electrolytic polymerization. In addition, the anode body having the dielectric coating formed thereon is molded into a predetermined shape such as, for example, a substantially rectangular parallelepiped. It has been found, however, that this method for forming the solid electrolyte layer (polymerization) and the shape of the anode body may make it difficult in some cases to form the solid electrolyte layer having an uniform thickness on a surface of the dielectric coating. Therefore, the inventor of the present invention has confirmed that an electrical short circuit may occur between the anode body and the cathode layer (the carbon layer and the silver paste layer) particularly at a relatively thin portion of the solid electrolyte layer.